That's a lot of conversions...
107*7 = 749km in one week
749/1.6 = 468.125 miles
468.125/39 = <span>12.0032051282 gallons of fuel needed
</span>1 gallon = 4.54609 litres
1.1(Cost per litre)*4.54609(Number of litres per gallon)*12.0032051282(Number of gallons needed) = <span>60.0244158814 euros cost per week
</span>60.0244158814 * 1.26 = <span>75.6307640105 dollar cost per week
</span>$75.63
<span>64.94
First, write out an expression about what we know
0.6915 * 62.93 + 0.3085 * x = 63.55
Now solve for x
0.6915 * 62.93 + 0.3085 * x = 63.55
43.5161 + 0.3085 * x = 63.55
0.3085 * x = 20.03391
x = 64.93972
Rounding the answer to 2 decimal places gives x = 64.94</span>